3GPP (3rd Generation Partnership Project), which is a project aiming to standardize a mobile communication system, plans to promote the standardization of CoMP (Coordinated Multi-Point) in its release 11 onward (see Non Patent Literature 1).
In CoMP, an antenna group arranged in the same place is positioned as one “point” and a plurality of points communicate with a user terminal in cooperation with one another. A point group that performs cooperative communication with a user terminal by using one time and frequency resource is called a CoMP cooperating set.
Furthermore, a form of CoMP is Intra-Site CoMP. In Intra-Site CoMP, when a user terminal is positioned in a boundary region of a plurality of cells belonging to one base station, each cell is considered as a “point”, and the plurality of cells perform CoMP communication with the user terminal. Thus, the throughput in the cell boundary region can be improved.
In addition, it is noted that a “cell” is used as a term indicating a unit of a radio communication area, and is also used as a term indicating a function of performing radio communication with a user terminal. Furthermore, a “cell” is also called a “sector”.